<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.7.16/dist/vue.js"></script>
    <link href="./CSS/demo1.css" rel="stylesheet">
</head>
<body>
<div id="root">
    <div class="header">
        <div>{{result}}{{numOld}}&nbsp;{{operVar}}</div>
        <div>{{numNew}}</div>
    </div>
    <div class="content">
        <div v-for="item in val">
            <button :value="item" @click="valClick(item)">{{item}}</button>
        </div>
    </div>

</div>
<script src="./JS/demo1.js"></script>

</body>
</html>